The present invention relates to the binding of a plurality of sheets of paper, or the like, having aligned peripheral apertures. In typical practice of today, plastic binding elements mainly comprise curved flat plastic fingers attached to a longitudinally extending backbone element and arranged to cooperate with a plurality of generally rectangular pre-punched apertures along one edge of the paper. The desirability of a completely lie-flat binding element for such articles as calendars, and the like, has made it desirable to provide one or more rings entirely separate from any backbone. Further, an examination of the problem of binding books in a looseleaf manner at extremely high speed has been reviewed and prior art systems, particularly those employing the integral backbone and finger-binding elements have been found operating now at a low but nearly maximum rate.
Such prior art integral backbone and finger binding elements are conventionally applied to a preformed perforated sheet by the spreading of all of the backbone fingers simultaneously with the transverse motion of the perforated sheets into position in the binding, followed by release of all of the fingers and simultaneous engagement with all of the apertures of the sheets being bound. In accordance with the present invention, however, the perforated sheets being bound may be introduced into the apparatus from a direction parallel to the line of perforations along the edge of the sheets and individual rings inserted sequentially as the book passes through the apparatus. As a result of the sequential binding with a plurality of single rings, the speed of binding is tied only to the edgewise speed of the book conveyor, and, accordingly, I have found that the capability of extremely high-speed bookbinding has been increased by at least 100% over previously known plastic binding systems.
While prior art binding has on occasion been accomplished by a ring element having a radial slot, the effective closure of the slot in an effective manner has not, to my knowledge, been successfully accomplished. In accordance with the present invention, the radial slot provided in the manufacture of the ring binder is substantially completely closed inherently and mechanical interlock means are provided in the ring construction to physically prevent disassembly of sheets in normal use.